Superphosphates

As Superphosphates different as are fertilizer used Phosphate referred, which differ in their phosphate content and water-side components.

history

Around the beginning of industrialization , in the 1830s, fertilizer was initially imported from Chile for agriculture to Europe and to the area of the German Confederation as so-called " Chile nitrate ". After the introduction of guano from Peru in the 1840s, the "artificial" fertilizer in the form of superphosphate, which was initially only produced in England, was added for the first time. After the farmer Julius Kühn had produced superphosphate on a small scale from bone meal and sulfuric acid in the area of the later German Empire in 1850 , the Stackmann & Retschy company in Lehrte introduced “probably the first to manufacture superphosphate in Germany” in 1855.

At the suggestion of Justus von Liebig , the chemical factory in Schöningen also followed in 1858 . Field fertilization trials with superphosphate from Schöningen on sugar beets resulted in a record yield of 189.4 quintals per acre in 1859 . In contrast, the unfertilized sugar beet cultivation of a piece of land only reached 90.1 quintals per acre.

Superphosphate

The term superphosphate is not a standardized name for a chemical compound, but a trade name for a solid, granular product that contains water-soluble, i.e. water-soluble, phosphate.

To produce superphosphate , naturally occurring, water-insoluble calcium phosphate is digested with the help of sulfuric acid :

{\ displaystyle {\ ce {Ca3 (PO4) 2 + 2H2SO4 + 4H2O -> Ca (H2PO4) 2 + 2 [CaSO4.2H2O]}}}

In this way, water-soluble calcium dihydrogen phosphate is obtained in addition to approx. 60% water-insoluble calcium sulfate . This mixture contains (converted) 16-22% by weight of P ₂ O ₅ .

The process for making superphosphate was developed by the British agricultural chemist John Bennet Lawes . In 1843 he started producing the artificial fertilizer.

Double super phosphate

In contrast to superphosphate, no insoluble calcium sulfate is produced in the production of double superphosphate . For this purpose, insoluble calcium phosphate , which occurs naturally in association with calcium carbonate , is reacted with technical phosphoric acid:

{\ displaystyle {\ ce {Ca3 (PO4) 2 + 4H3PO4 -> 3Ca (H2PO4) 2}}}

The resulting double superphosphate contains the equivalent of 35% by weight P ₂ O ₅ .

Triple superphosphate

A fertilizer containing calcium dihydrogen phosphate is referred to as triple superphosphate (also triple superphosphate ) which, when converted, has a content of more than 46% by weight P ₂ O ₅ . This can be achieved, for example, if phosphoric acid with a higher purity is used instead of the technical grade phosphoric acid, which is used for the production of double superphosphate.

literature

AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 91st – 100th, improved and greatly expanded edition. Walter de Gruyter, Berlin 1985, ISBN 3-11-007511-3 , p. 775.
A. Messerschmidt, L. Seidler: Fertilizers, artificial , in Fritz Ullmann (Ed.): Enzyklopädie der Technischen Chemie , Vol. 2nd, 2nd edition, Berlin; Vienna: Urban & Schwarzenberg, 1929, pp. 24–91.
Hans Werner Schütt : Beginnings of agricultural chemistry in the first half of the 19th century , in: Zeitschrift für Agrargeschichte und Agrarsoziologie , Vol. 21 (1973), pp. 82–91.
Lothar Naumann : On the influence of agricultural use on the landscape factor soil under the aspect of state maintenance, presented in selected areas in Lower Saxony , at the same time dissertation from February 6, 1970 at the Faculty of Horticulture and Regional Culture of the Technical University of Hanover, Hanover, 1970; contents
Gerhard K. Schmidt: "Stackmann & Retschy" , in ders .: One hundred years of the city of Lehrte 1898 - 1998. From the village in the great outdoors to the city in the district , publisher: Stadt Lehrte, Lehrte: Stadt Lehrte, ISBN 978-3-00 -002634-8 and ISBN 3-00-002634-7 , ( table of contents ), p. 24 f.

Individual evidence

↑ Gerhard K. Schmidt: "Stackmann & Retschy" , in ders .: One hundred years of the city of Lehrte 1898 - 1998. From the village in the great outdoors to the city in the district , publisher: Stadt Lehrte, Lehrte: Stadt Lehrte, ISBN 978-3- 00-002634-8 and ISBN 3-00-002634-7 , ( table of contents ), p. 24 f.
^ Justus von Liebig : Letters to Vieweg . Vieweg and Teubner, Wiesbaden 2013, p. 315; 321, ISBN 978-3-663-19706-5
^ Wilhelm Rimpau : Fertilization experiments with sugar beets, in particular with the use of fertilizers rich in phosphorus . In: The chemical farm man . Volume 5, Adolph Stöckhardt (Ed.), Verlag Georg Wigand, Leipzig 1859, pp. 102-110.

[1] Gerhard K. Schmidt: "Stackmann & Retschy" , in ders .: One hundred years of the city of Lehrte 1898 - 1998. From the village in the great outdoors to the city in the district , publisher: Stadt Lehrte, Lehrte: Stadt Lehrte, ISBN 978-3- 00-002634-8 and ISBN 3-00-002634-7 , ( table of contents ), p. 24 f.

[2] Justus von Liebig : Letters to Vieweg . Vieweg and Teubner, Wiesbaden 2013, p. 315; 321, ISBN 978-3-663-19706-5

[3] Wilhelm Rimpau : Fertilization experiments with sugar beets, in particular with the use of fertilizers rich in phosphorus . In: The chemical farm man . Volume 5, Adolph Stöckhardt (Ed.), Verlag Georg Wigand, Leipzig 1859, pp. 102-110.